Nanoparticles (“NPs”) have been reported to have a wide range of applications in electronics, optics, catalysis and biotechnology. The physical properties (e.g., high surface-to-volume ratio, elevated surface energy, increased ductility after pressure loading, higher hardness, larger specific heat and the like) of NPs have led to a variety of applications in the material-directed industry and material science. For example, a variety of metal NPs have been used to catalyze numerous reactions and semiconductor NPs are used as fluorescent probes.
Single particle electrochemical sensors, which employ an electrochemical device for detecting single particles, have also been reported. Methods for using such a device to achieve high sensitivity for detecting particles such as bacteria, viruses, aggregates, immuno-complexes, molecules, or ionic species have been described.
The use of colloidal particles in sensing arrays have also been reported. These are chemical sensors for detecting analytes in fluids via arrays having a plurality of alternating nonconductive regions and conductive regions of conductive NP materials. Variability in chemical sensitivity from sensor to sensor is reported to be provided by qualitatively or quantitatively varying the composition of the conductive and/or nonconductive regions.
The size of nanostructured materials (“NSMs”) generally ranges from less than 1 nm to several hundred nm at least in one dimension and the electronic energy band configuration is a size-dependent property, which in turn can affect the physical and chemical properties. A fundamental distinction between NSMs and bulk materials is that the fraction of surface atoms and the radius of curvature of the surface of NSMs are comparable with the lattice constant. As a result, nanostructured materials generally have higher activity as compared with their analogues based on bulk materials. A number of methods of forming NSMs are known to the skilled artisan and include formation by combining atoms (or more complex radicals and molecules) and by dispersion of bulk materials, e.g., thermal evaporation, ion sputtering, reduction from solution, reduction in microemulsions, and condensation.